/Engine/Source/Runtime/UMG/Public/Blueprint/UserWidget.h
virtual void NativeOnFocusChanging ( const [FWeakWidgetPath](API\Runtime\SlateCore\Layout\FWeakWidgetPath) & PreviousFocusPath, const [FWidgetPath](API\Runtime\SlateCore\Layout\FWidgetPath) & NewWidgetPath, const [FFocusEvent](API\Runtime\SlateCore\Input\FFocusEvent) & InFocusEvent )